The incidence of esophageal adenocarcinoma is rising more rapidly than that of any other malignancy. The presence of Barrett's mucosa, a metaplastic columnar epithelium located in the esophagus, identifies persons at risk for esophageal adenocarcinoma. Thus, there is a compelling rationale for characterizing the environmental, behavioral, or genetic factors associated with Barrett's metaplasia development, and describing the risk factors for its progression to neoplasia. Hypotheses: A. People with Barrett's metaplasia have different intakes of fats and medications that relax the lower esophageal sphincter (e.g. calcium channel blockers, beta-agonists, anticholinergic agents) than do controls. B. Environmental risk factors play a role in the rates of neoplastic progression of Barrett's metaplasia to adenocarcinoma. Specific Aims/Methods: A. Perform a population based case-control study of patients with Barrett's metaplasia (using a large health maintenance organization) to evaluate whether fats and medications that relax the lower esophageal sphincter are risk factors for this pre-malignant conditions. This will use direct patient contact, validated nutritional questionnaires, and a pharmacy database of medications previously prescribed. B. Use the Barrett's metaplasia and control patients evaluated in this pilot study as a population-based cohort for future follow-up studies of neoplastic progression rates to adenocarcinoma, risk stratification for development of adenocarcinoma based on demographic and environmental factors, evaluation of adenocarcinoma surveillance/no surveillance groups, and comparison of Helicobacter Pylori infection status between Barrett's patients and controls. When completed, this future study will provide needed information on absolute risk of adenocarcinoma in different risk groups and allow completion of informed cost- effectiveness analyses for endoscopic surveillance programs.